The present invention relates to a scanning-type laser marking apparatus which uses a laser beam spot to scan a surface of a workpiece to thereby mark a desired pattern.
In the scanning-type laser marking method, a highly focused laser beam is projected onto a workpiece. The laser beam is swung by a scan mirror so that a beam spot of the laser beam scans a surface of the workpiece. A point on the workpiece surface where the laser beam spot hits is vaporized or altered in color instantly by the laser beam energy. The laser beam scanning or drawing results in marking a desired pattern of a character, figure and/or symbol on the workpiece surface.
In general, the scanning-type laser marking apparatus comprises a laser oscillator which oscillates and outputs a laser beam, a scanning head which swings the laser beam from the laser oscillator for projection onto the workpiece and a control which controls the operation (laser oscillation and laser beam scanning) of the laser oscillator and the scanning head.
The scanning head is fixed with the laser beam outlet directed to a marking point on a work bench. A software scanning coordinate viewed from the apparatus is predetermined for the workbench. A workpiece is placed on a workbench so that a marking surface of the workpiece is directed to the laser outlet of the scanning head. By changing the position and direction of the workpiece on the workbench, the workpiece marking position where the pattern is to be formed can be adjusted.
In the scanning-type laser marking apparatus, the pattern to be marked on a workpiece has a position, extension and direction in the scanning coordinate system. Thus, the workpiece positioning involves adjusting the workpiece position in the X (horizontal), Y (vertical) and .theta. (rotation) directions. For adjustment of the marking position on the workpiece the prior art actually marks a desired pattern on a workpiece sample. An operator evaluates an error of the result (marking position) from the desired position and adjusts the workpiece position based on the evaluated error.
The prior method of workpiece positioning is done on a trial and error basis by performing actual marking operations. Thus, the prior art method not only wastes or consumes laser oscillator and workpiece samples but also requires extensive time and procedures for the workpiece positioning. Therefore, the prior art method has the problem of low productivity.
The laser marking method can use computer technology to prepare a large number of patterns which can be arbitrarily changed or edited and to simply select a desired pattern for marking. Conventional laser marking patterns include a character or character string indicative of a product name, corporation name, manufacturing number or the like.
To set the pattern of a character (character string) in the prior art scanning laser marking apparatus, a user not only enters, by key operation, the desired character (character string) but also enters various parameters defining the layout of the character (character string) pattern including layout direction of the character or character string (horizontal, vertical, horizontal curve, vertical curve), x-start point, y-start point, character (character string) height, character (character string) width, character pitch, etc., by specifying desired numeric data, respectively. The apparatus uses the entered parameters to determine the layout. Then the apparatus determines the pattern of the character (character string) with the layout and stores the pattern data into a memory.
The user can confirm the entered character pattern on a display screen. If a layout change is required, the parameter values may appropriately be changed. A plurality of character fonts may be provided to allow a user to select a desired font.
Setting the character pattern in the prior art, however, requires complicated decisions and operations on the part of the user. In particular, when determining a layout, a user must enter the desired character pattern and character spacing by numeric data of various parameters. Except for a highly skilled operator, the layout determining procedure takes excessive time and labor since the parameter values may be changed many times to get the desired layout.